1. Field of the Invention
The present invention generally relates to a recording medium capable of recording main data such as audio data for example and auxiliary data such as character information and image information for example, a recording apparatus compatible with this recording medium, and a reproducing apparatus compatible with this recording medium.
2. Description of Related Art
A recording and/or reproducing apparatus that uses a recording medium such as a magneto-optical disc for digitally recording an audio signal or a magnetic tape is known as a recording and/or reproducing apparatus for recording and/or reproducing music data and so on.
A recording and/or reproducing system that uses magneto-optical disc known as a Mini Disc (trademark) allows its user not only to record and reproduce an audio signal such as of music as a program but also to record as character information a disc name, which is a disc title name, and a track name, which is a music title, of each program of recorded music. At the time of reproduction of a piece of music for example, its disc title, music title, artist name, and other recorded character information can be displayed on the display monitor arranged on the reproducing apparatus.
It should be noted that the term "program" used herein denotes the unit of audio data such as music as the main data to be recorded on a disc. For example, one piece of music of audio data provides one program. It should also be noted that the term "track" is also used hereafter to denote the above-mentioned program.
In the Mini Disc system, the information recorded as a disc name and a track name is not so large in size; namely, the information is only sufficient in size to record the number of characters constituting several titles such as mentioned above. To be more specific, in control information U-TOC (User Table Of Contents) for controlling a program recording and/or reproducing operation, character information for each program can be recorded and its recordable size is not so large. For example, a comparatively large size of character information such as a lyrics text of a song recorded as a program cannot be recorded in a U-TOC.
In addition, the character information in a U-TOC is only related to a program as a whole; namely, it is not related to a particular reproducing position in a piece of music for example as a program. Therefore, a character information display timing cannot be set, according to a play position, to music to be reproduced. For example, even if a comparatively large size of character information equivalent to a lyrics text of music can be recorded, the lyrics text cannot be displayed in synchronization with the progress of the play. For example, displaying a lyrics text in synchronization with a vocal or for lyrics text guiding in karaoke playing.
However, recording a comparatively large size of character information such as a lyrics text and outputting for display the character information in synchronization with music play timing is enabled by recording the character information not in a U-TOC but an area called an auxiliary data area. CD-Graphics is known as a system for recording character information in such an auxiliary area to display a lyrics text.
This will be detailed with reference to FIG. 2. In the case of a Mini Disc system, the data unit called a cluster provides the basic unit of a recording operation. This cluster has an area of 32 sectors in which audio data is recorded as a program and an area in which one sector of auxiliary data is recorded. Therefore, storing the character information such as a lyrics text corresponding to the audio data stored in a cluster onto the auxiliary data area in each cluster can record a comparatively large size of lyrics text information and output the recorded information for display in synchronization with the play of music.
However, the above-mentioned use of auxiliary data involves following problems.
Because a recording operation is performed with one cluster as a minimum unit, auxiliary data alone cannot be recorded. Therefore, because additional recording of auxiliary data alone is disabled, if an attempt is made to additionally record character information providing a lyrics text onto auxiliary data for a recorded piece of music to be rewritten, all of the audio data, which is the main data, and the auxiliary data, which is character information, must be recorded again. This holds true with modifying character information. Hence, additional writing or modification of character information or adjustment of display timing is not necessarily impossible but is burdensome and takes time.
In other words, in additionally recording character information onto auxiliary data, the audio data, which is the main data, must be reproduced in a predetermined amount and the reproduced audio data must be stored in memory. Then, the stored audio data must be read on a cluster basis and character information must be added to the auxiliary data portion to be recorded onto disc again.
In addition, because character information comes to be controlled strictly as a complete accompaniment to a program, flexible handling of character information is disabled, thereby hampering the future system expansion.